[Early stage Stewart-Treves syndrome: report of 2 cases and review of the literature].

BACKGROUND: Stewart-Treves (S-T) syndrome is a rare from of angiosarcoma occurring as a complication of lymphedema, classically associated with mastectomy and lymph node dissection for breast carcinoma but also occurring in other forms of chronic lymphoedema. Generally S-T syndrome has a very poor prognosis. Recognition in its earliest stages, at least histologically, can be extremely difficult.

MATERIALS AND RESULTS: We report two female patients aged 77 and 68 with chronic lymphoedema of the arm complicating for 9 and 8 years respectively ipsilateral mastectomy for breast cancer treated 10 years earlier in both cases. The first developed violaceous macules on the arm and the second presented with a bluish cutaneous nodule on the upper arm. Histologically the first showed lymphangectasia and a dermal proliferation of thin-walled dissecting vessels with only focally slight endothelial atypia ("lymphangiomatosis"), whereas similar architectural features in the second case were associated focally with overt endothelial atypia and micropapillae. These appearances were regarded as pre-malignant (lymphangiomatosis) and malignant (angiosarcoma) respectively. At 3 years follow-up the first patient showed no disease progression, whereas the second patient at her second year of follow-up developed additional nodules.

DISCUSSION: In reviewing the literature, approximately 400 cases of angiosarcoma associated with lymphoedema have been reported, of which 360 occurred after ipsilateral mastectomy. Previous controversy as to whether such tumors were truly vascular (rather than simply recurrent carcinoma) has been resolved conclusively in favour of endothelial differentiation. Pathogenetically it seems in these cases that chronic lymphoedema histologically characterized by lymphatic dilatation (lymphangectasia) leads first to proliferation of lymphatics (lymphangiomatosis) with possible slight endothelial atypia. Thereafter there is a gradual continuum of increasing endothelial atypia, followed by multilayering, papillae formation and solid sheet-like tumour. Cumulative published data show that lymphangiomatosis in this clinical setting is premalignant, while the presence of moderate to severe endothelial atypia indicates a diagnosis of (lymph) angiosarcoma. Histological distinction between lymphangiomatosis and ("early") well-differentiated angiosarcoma can be difficult but clearly is of great clinical importance.